As a general structure for automotive interior components such as door trims, there is known the laminated structure in which a surface skin member having a cushioning and favorable appearance quality is bonded over a surface of a core member having the capability to retain its shape and the rigidity required for mounting it on a door panel.
FIG. 9 shows the structure of an automotive door trim 1 given here as a typical example of automotive interior component. In this door trim 1, a surface skin member 3 is integrally bonded over a surface of a resin core member 2 molded into a desired shape, and this surface skin member 3 consists of a surface skin sheet 4 with a back lining of a foamed layer 5 of such a material as polyethylene foam or polypropylene foam to ensure a necessary buffering or cushioning and ornamental quality. Along the edge of the product, the surface skin member 3 is folded over and bonded to the reverse surface of the resin core member 2 along its edge to produce a favorable edge finish.
To realize such a structure, as shown in FIG. 10, a bonding agent 6 is applied to a reverse surface of a peripheral portion 2a of the resin core member 2 and a reverse surface of a peripheral portion 3a of the surface skin member 3 extending beyond the edge of the resin core member 2 so that the peripheral portion 3a of the surface skin member 3 may be securely attached to the peripheral portion 3a of the reverse surface of the resin core member 3 by means of the bonding capability of the bonding agent 6.
When a tactic resin such as polypropylene is used as the material for the resin core member 2 by taking into account such considerations as cost, moldability and mechanical strength, since the tactic resin is chemically stable and lacks the bonding capability based on chemical or ionic bonding, it is necessary to make the surface reasonably coarse by using sand paper or the like or to apply a primer layer 7 (such as carbontetrachloride) thereon, as illustrated in FIG. 11, before applying a coating of the bonding agent 6.
Thus, according to the conventional automotive interior component, since the folded back peripheral portion 3a of the surface skin member 3 is secured by adhesive bonding, the edge processing for the surface skin member required the three steps of applying a bonding agent thereto, drying (reactivating) the bonding agent, and bonding of the folded back peripheral portion 3a, and these steps required such devices and facilities as a bonding agent applying booth, an oven and a bonding device which contribute to a substantial increase in manufacturing cost.
Further, since the bonding agent contains an organic solvent, the working environment is not favorable, and a ventilation system such as a ventilation duct becomes necessary to expel the solvent from the working environment. Thus, the need for facilities related to the use of a bonding agent also contributes to the increase in cost.